docs: def get_properties(properties, identifier, namespace='cid', searchtype=None, as_dataframe=False, **kwargs):
      """Retrieve the specified properties from PubChem.
  
      :param identifier: The compound, substance or assay identifier to use as a search query.
      :param namespace: (optional) The identifier type.
      :param searchtype: (optional) The advanced search type, one of substructure, superstructure or similarity.
      :param as_dataframe: (optional) Automatically extract the properties into a pandas :class:`~pandas.DataFrame`.
      """
      if isinstance(properties, text_types):
          properties = properties.split(',')
      properties = ','.join([PROPERTY_MAP.get(p, p) for p in properties])
      properties = 'property/%s' % properties
      results = get_json(identifier, namespace, 'compound', properties, searchtype=searchtype, **kwargs)
      results = results['PropertyTable']['Properties'] if results else []
      if as_dataframe:
          import pandas as pd
          return pd.DataFrame.from_records(results, index='CID')
      return results